Spray-up and gel coating, resin transfer molding (RTM) and other less important procedures like pouring or casting of polyester require the controlled combination of resin with catalyst.
Heretofore, various means have been used for metering catalyst including:
Venturi tube and needle valve into air stream from a pressure pot. The air stream with atomized catalyst is then used to spray the polyester resin. The catalyst metered is proportional to airflow. PA1 It has also been proposed to meter with only a pressure pot and needle valve. This method uses less air and therefore possibly poisons the environment less than the first method. PA1 Another approach involves metering with a catalyst pump which is not slaved to the resin pump but pumps at a constant rate. PA1 a cylinder, PA1 a piston within said cylinder, PA1 a hollow rod connected to said piston, said piston and hollow rod being reciprocable within said cylinder, an opening in the face of said piston and a check valve for regulating flow through said piston and into said hollow rod, PA1 a first fixed plug forming one end of said cylinder, a check valve in the face of said plug for regulating flow through said plug, and an inlet passage communicating with the valve in the plug for introducing liquid into said cylinder, PA1 a second fixed plug at the opposite end of said cylinder, said hollow rod passing slidably therethrough, PA1 the interior of said hollow rod communicating with both the discharge passage for said pump and with the annular space within said cylinder between said piston and said second plug which surrounds the exterior of said rod, PA1 said check valves being disposed so that on the up stroke of the piston, the valve in the first plug is open while the valve in the piston is closed, and on the down stroke, the valve in the piston is open whereby fluid is discharged from said discharge passage on both the up stroke and the down stroke of said piston and hollow rod, the fluid discharged on the up stroke being displaced through said hollow rod due to the flow of fluid from said annular space and the fluid discharged on the down stroke being due to displacement of fluid through said hollow rod from the space between said first fixed plug and said piston, said down stroke also replenishing said annular space with fluid. PA1 a master reciprocating pump for pumping a first fluid such as liquid resin, PA1 a reciprocating slave pump for pumping a second fluid such as liquid catalyst, PA1 means for restraining one end of said slave pump in a fixed position with respect to the master pump, PA1 means for moving the other end of said slave pump relative to the end which is restrained, said means for moving being interconnected to and driven by the reciprocating portion of said master pump, both said means for restraining and means for moving having adjustment means whereby the extent of movement of said other end of said slave pump can be changed to thereby changing the ratio of resin to catalyst dispensed; PA1 the improvement wherein said means for moving include one or more articulated joints provided with spherical bearings.
In addition, there is at least one slave pump on the market, made by Venus Products, Inc. It is designed for metering catalyst into a spray gun which internally mixes resin and catalyst. The device is also the subject of U.S. Pat. No. 3,790,030. The present invention presents a significant advance thereover as will more fully hereinafter appear.
In the patent literature to Hoover (U.S. Pat. No. 2,954,737), Daby (U.S. Pat. No. 4,312,463) and Stephans (U.S. Pat. No. 3,612,732) disclose various pumping devices wherein a slave pump is mechanically interconnected to, or driven by, a master pump. In Hoover and Stephans the connection is by way of a fixed arm to which the slave pump cylinder is connected and a movable arm connected to the slave pump piston rod. In Hoover, the movable arm is driven by the master pump rod, while in Stephans the movable arm is driven via a cam mechanism. In the device of Daby, the master pump piston rod is mechanically connected to the slave pump piston rod via a movable arm. The hydraulic output of the slave cylinder drives a slave pump. The slave pump of Hoover utilizes a separate outer tube for the cylinder and contains all of the inlet, outlet, and valve structure in separate attachments at each end of the separate tube. In all three of these patents, the position of the slave cylinder is disclosed as being adjustable along the length of the movable arm in order to adjust the output of the slave pump. In each of these patents, pivoting connections are utilized between a slave pump and the fixed and movable arms.
The patent to Bentley (U.S. Pat. No. 4,349,321) shows a slave pump utilizing a separate outer tube without an inlet or an outlet. The respective inlets and outlets as well as the valving structure are connected in end units which are attached to the separate tube.
The patents to Buckley et al (U.S. Pat. No. 4,182,387), Robbins (U.S. Pat. No. 3,814,289), and Pensa (U.S. Pat. No. 3,694,108) show various means of attaching pumps to their actuating arms. In Buckley et al, universal joints are utilized to interconnect the pump cylinder and the piston rod to fixed and movable arms respectively. Robbins discloses a mixing apparatus utilizing a plurality of individual pumps wherein each of the pumps are connected to a common actuating rod. The connection between the pumps' piston rods and the actuating rods are by way of a roller-type structure. Pensa discloses the use of spherical bearings to interconnect the piston rods of a pump to a capacity adjusting mechanism.
The patents to Macosko et al (U.S. Pat. No. 4,189,070) and Robbins (U.S. Pat. No. 3,642,175) show pumping devices with slave pumps to inject a measured amount of material in conjunction with a master pump. In each case, a movable arm interconnects the piston rod of the master pump with the piston rod of the slave pump.
Some of these prior procedures have various drawbacks and disadvantages including air pollution and lack of adequate control of the proportioning of resin-to-catalyst. Others are excessively complex.